2014
2014
-
Record 277 of
Title:Tunable and switchable multi-wavelength dissipative soliton generation in a graphene oxide mode-locked Yb-doped fiber laser
Author(s):Huang, Shisheng(1); Wang, Yonggang(2); Yan, Peiguang(1); Zhao, Junqing(1); Li, Huiquan(1); Lin, Rongyong(1)Source: Optics Express Volume: 22 Issue: 10 DOI: 10.1364/OE.22.011417 Published: 2014Abstract:We report the generation of tunable single-, switchable and tunable dual-, and stable triple-wavelength dissipative solitons (DSs) in an all-normal-dispersion mode-locked Yb-doped fiber laser based on a graphene-oxide saturable absorber (GOSA) without additional components (such as optical filter, or fiber grating). The tunable single-wavelength DS have a wide wavelength-tunable range of 16.4 nm. The dual-wavelength DSs not only have a wavelength-tunable range (about 10 nm) but also have variable wavelength spacing (3.8-13.8 nm). The formation dynamics of the triple-wavelength DSs was also investigated experimentally. The different operations of tunable single-, switchable and tunable dual-, and stable triple-wavelength DSs depend on the strength of the cavity birefringence. The simple, compact all-fiber DS laser with lasing wavelength tunability and flexibility can meet great potential for applications. ? 2014 Optical Society of America.Accession Number: 20142217768218 -
Record 278 of
Title:Focus shaping of radial polarized beam based on pupil filter
Author(s):Zhu, Huafeng(1,2); Wang, Tianyang(2); Liu, Pei(2); Fu, Jianbo(2); Li, Dailin(2); Wang, Ning(2); Wang, Xiumin(2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: DOI: 10.3788/AOS201434.s126001 Published: September 10, 2014Abstract:The optical intensity distribution in the focal volume plays an important role on the performance for many optical systems. Effective manipulation of focused optical intensity distribution can be obtained by using a pupil filter composed by zonal optical diffractive element and zonal double half-wave plate which can modulate both the phase and the direction of polarization of incident radially polarized beam zone by zone, and turn radially polarized beam into zonal sylindrically polarized beam. Numerical simulations of Matlab show that different intensity distributions can be obtained in the focal volume. Using the method, besides the existing doughnut intensity distribution and flattop focal spot in focal plane, the flattop doughnut intensity in the focal plane with hollow three-dimension (3D) pattern is obtained. This result can find potential use in fields such as particle manipulation and caption, laser micromachining, etc.Accession Number: 20144100087854 -
Record 279 of
Title:Design and fabrication of cyclic-olefin copolymer based hollow-core microstructured terahertz fiber
Author(s):Ji, Jiangjun(1); Kong, Depeng(1); Ma, Tian(1); He, Xiaoyang(2); Chen, Qi(2); Wang, Lili(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 6 DOI: Published: June 2014Abstract:A hollow-core porous microstructured terahertz fiber based on Topas cyclic-olefin polymer (COC) was designed and manufactured. The loss characteristics of an optical fiber with outer diameter 10 mm was simulated using comsol software in the 0.2-1.5 THz band. There are several low-loss bands in the 0.85 -1.5 THz, and there are three windows in which the loss is lower than 3 dB/m in the 0.85 -1.1 THz band, the loss is about 0.208 dB/m especially in the 0.99 THz. By comparing the loss characteristics of the fiber with core diameter of 3 mm, 4.8 mm and 6 mm in 0.8-1.5 THz band, the loss was reduced with increasing the diameter. The outer diameter of designed THz fiber was enlarged to 7 cm, and a dedicated mold was designed for manufacturing preform. A 22 cm long THz fiber preform with a standard structure and smooth surface was manufactured by the hot extrusion molding method. Finally, through the laboratory's unique draw tower, the terahertz fiber of the core diameter of 3 mm, 4.8 mm and 6 mm were manufactured. The loss analysis result show that the average loss of the fiber with core diameter of 6mm is 2.175 dB/m in 1.27 THz and it is near the theoretical loss (1.95 dB/m).Accession Number: 20142917960088 -
Record 280 of
Title:Raman spectroscopy and periodic surface structures of Mg:ZnO thin film fabricated by femtosecond laser pulses
Author(s):Wang, Hongying(1,2); Cheng, Zhen(1); Cheng, Guanghua(3); Ma, Fei(4); Li, Yuanyuan(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9126 Issue: DOI: 10.1117/12.2051212 Published: 2014Abstract:Mg doped ZnO thin films were prepared by magnetron sputtering and were irradiated by linearly polarized femtosecond laser pulse. Scanning electron microscopy (SEM) characterizations illustrated that regularly arranged nanoripples appeared on the ablation area with the period perpendicular to the polarization direction in the range of 250 nm~570 nm, but parallel to the polarization direction in the range of 2.2 μm~2.5 μm. The redshift of Raman peaks was observed at the central ablation area of the nanoripples, while, both blueshift and redshift were found at the edge area, which could be ascribed to the defects as well as the nanoripple structure. ? 2014 SPIE.Accession Number: 20142517849994 -
Record 281 of
Title:Ytterbium-doped large-mode-area silica fiber fabricated by using chelate precursor doping technique
Author(s):Shi, Tengfei(1,2); Zhou, Zhiguang(1); Ni, Li(1); Xiao, Xusheng(1,2); Zhan, Huan(1,2); Zhang, Aidong(1); Lin, Aoxiang(1)Source: Applied Optics Volume: Issue: 15 DOI: 10.1364/AO.53.003191 Published: May 20, 2014Abstract:We reported on a highly effective chelate precursor doping technique for Yb-doped large-mode-area (LMA) fiber manufacture. By accurately controlling the evaporation temperature and flow rate of carrier gas, the chelate precursor doping technique is capable of making Yb-doped LMA silica fiber with good uniformity free of center dip, low numerical aperture of ～0.056, large preform core size of 4.46 mm, and appropriate cladding absorption of 1.17 dB/m at 976.4 nm. Based on a single-end-pump all-fiber oscillator laser setup, the laser output at 1080 nm reached 700 W with slope efficiency of 54.2%. ? 2014 Optical Society of America.Accession Number: 20141200000778 -
Record 282 of
Title:Line-plane-switching infrared fiber imaging bundle
Author(s):Zhan, Huan(1,2); Yan, Xingtao(1,2); Zhang, Aidong(1); Li, Fu(1); Yang, Jianfeng(1); Lin, Aoxiang(1)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: 10.1364/cleo_at.2014.jth2a.24 Published: 2014Abstract:Using line-plane-switching infrared fiber imaging bundle made from As2S3 glass fibers with core of 40 μm, clad of 45 μm, and error of 1% in diameter, we demonstrated push-broom infrared sensing imaging. ? 2014 OSA.Accession Number: 20143318056228 -
Record 283 of
Title:Shrink image by feature matrix decomposition
Author(s):Wang, Qi(1); Li, Xuelong(2)Source: Neurocomputing Volume: 140 Issue: DOI: 10.1016/j.neucom.2014.03.025 Published: September 22, 2014Abstract:With the development of multimedia technology, image resizing has been raised as a question when the aspect ratio of an examined image should be displayed on a device with a different aspect ratio. Traditional nonuniform scaling for tackling this problem will lead to distortion. Therefore, content-aware consideration is mostly incorporated in the designing procedure. Such methods generally defines an energy function indicating the importance level of image content. The more important regions would be retained in the resizing procedure and distortion could be avoided consequently. The definition of the related energy function is thus the critical factor that directly influences the resizing results. In this work, we explore the definition of energy function from another aspect, matrix decomposition of Low-rank Representation. In our processing, a feature matrix that reflects the texture prior of object contour is firstly constructed. Then the matrix is decomposed into a low-rank one and sparse one. The energy function for resizing is then inferred from the sparse one. We illustrate the proposed method through seam carving framework and image shrinkage operation. Experiments on a dataset containing 1000 images demonstrate the effectiveness and robustness of the proposed method. ? 2014 Elsevier B.V.Accession Number: 20142217778044 -
Record 284 of
Title:Intense red fluorescence from Ho/Yb codoped tellurite glasses
Author(s):He, Jianli(1,2); Zhou, Zhiguang(1,2); Zhan, Huan(1,2); Lin, Aoxiang(1)Source: Journal of Non-Crystalline Solids Volume: 383 Issue: DOI: 10.1016/j.jnoncrysol.2013.04.051 Published: January 1, 2014Abstract:By optimizing the concentration ratio of Ho/Yb and using conventional melting and quenching methods, a group of Ho/Yb co-doped tellurite glasses with host composition of 78TeO2-12ZnO-10Na2O (mol.%, TZN) were made for red fiber laser development. Excited by 976 nm laser diode, intense green and red emissions were detected easily even by naked eyes. TZN glass codoped with 0.5 wt.% Ho2O3 and 3 wt.% Yb 2O3 was found to present the strongest red emission with the intensity about three times higher than that of the green one, presenting a yellowish-orange color as observed. Besides direct energy transfer process from Yb to Ho as usual, it is believed that cooperative energy transfer upconversion from a pair of Yb donor ions to one Ho acceptor ion and excited state absorptions among different levels of Ho ion are commonly responsible for the observed intense red emission. ? 2012 Elsevier B.V. All rights reserved. ? 2013 Elsevier B.V. All rights reserved.Accession Number: 20135117098598 -
Record 285 of
Title:Near- and mid-infrared emissions of Dy3+ doped and Dy 3+/Tm3+co-doped lead cesium iodide modified chalcohalide glasses
Author(s):Guo, Haitao(1); Xu, Yantao(1); Chen, Hongyan(2); He, Xin(3); Cui, Xiaoxia(1); Wang, Pengfei(1); Lu, Min(1); Li, Weinan(1); Hou, Chaoqi(1); Peng, Bo(1)Source: Journal of Luminescence Volume: 148 Issue: DOI: 10.1016/j.jlumin.2013.11.011 Published: April 1, 2014Abstract:0.2 wt% Dy3+ doped and 0.2 wt% Dy3+/0.5 wt% Tm 3+ co-doped novel GeS2-Ga2S3-PbS-CsI chalcohalide glasses were prepared and their spectroscopic properties were analyzed based on absorption (ranges from 300 to 3000 nm) and emission (ranges from 1000 to 4700 nm) measurements. Judd-Ofelt analyses were performed to estimate radiative transition parameters for the excited levels. Compositional dependences of near- and mid-infrared luminescences (especially the 1330, 2930 and 4320 nm) excited at 808 nm were investigated and discussed. These novel chalcohalide glasses may have potential uses in 1.3 μm fiber-amplifiers and 2.9 or 4.3 μm mid-infrared laser devices. ? 2013 Elsevier B.V.Accession Number: 20135217129074 -
Record 286 of
Title:Transition from Eu3+ to Eu2+ in SiO2 matrix prepared by sol-gel
Author(s):Zhang, Dekai(1,2); Hu, Xiaoyun(1,2); Jing, Guangyin(1,2); Liu, Enzhou(4); Fan, Jun(4); Zhang, Guodong(1); Hou, Xun(1,3)Source: Journal of Nanoscience and Nanotechnology Volume: 14 Issue: 5 DOI: 10.1166/jnn.2014.8023 Published: May 2014Abstract:Activated silica matrix fluorescent materials doped with Al3+ and Eu2+ are prepared by sol-gel method. The effects of different atmospheres and annealing temperatures on luminescent properties are characterized by analysis techniques including X-ray diffraction, infrared spectroscopy and fluorescence spectra. When being excited at 281 nm wavelength, the fluorescent materials show a strong broad blue emission band, with the emission center at 430 nm and the FWHM of 56 nm. The results indicate that the blue emission is derived from 4f6 5d to 4f7 transition of the Eu2+ ions. Al3+ ion plays a key role in the process of deoxidization from Eu3+ to Eu2+. Al3+ and B3+ can enhance the blue-emission intensity. Also it is found that the highest luminescent intensity of the samples occurs in the sample Eu-03 annealed at 1150 °C in N2 atmosphere. Copyright ? 2014 American Scientific Publishers.Accession Number: 20141617585519 -
Record 287 of
Title:Spectral embedded hashing for scalable image retrieval
Author(s):Chen, Lin(1); Xu, Dong(1); Tsang, Ivor Wai-Hung(1); Li, Xuelong(2)Source: IEEE Transactions on Cybernetics Volume: 44 Issue: 7 DOI: 10.1109/TCYB.2013.2281366 Published: July 2014Abstract:We propose a new graph based hashing method called spectral embedded hashing (SEH) for large-scale image retrieval. We first introduce a new regularizer into the objective function of the recent work spectral hashing to control the mismatch between the resultant hamming embedding and the low-dimensional data representation, which is obtained by using a linear regression function. This linear regression function can be employed to effectively handle the out-of-sample data, and the introduction of the new regularizer makes SEH better cope with the data sampled from a nonlinear manifold. Considering that SEH cannot efficiently cope with the high dimensional data, we further extend SEH to kernel SEH (KSEH) to improve the efficiency and effectiveness, in which a nonlinear regression function can also be employed to obtain the low dimensional data representation. We also develop a new method to efficiently solve the approximate solution for the eigenvalue decomposition problem in SEH and KSEH. Moreover, we show that some existing hashing methods are special cases of our KSEH. Our comprehensive experiments on CIFAR, Tiny-580K, NUS-WIDE, and Caltech-256 datasets clearly demonstrate the effectiveness of our methods. ? 2013 IEEE.Accession Number: 20142717881495 -
Record 288 of
Title:Double constrained NMF for hyperspectral unmixing
Author(s):Lu, Xiaoqiang(1); Wu, Hao(2); Yuan, Yuan(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 52 Issue: 5 DOI: 10.1109/TGRS.2013.2265322 Published: May 2014Abstract:Given only the collected hyperspectral data, unmixing aims at obtaining the latent constituent materials and their corresponding fractional abundances. Recently, many nonnegative matrix factorization (NMF)-based algorithms have been developed to deal with this issue. Considering that the abundances of most materials may be sparse, the sparseness constraint is intuitively introduced into NMF. Although sparse NMF algorithms have achieved advanced performance in unmixing, the result is still susceptible to unstable decomposition and noise corruption. To reduce the aforementioned drawbacks, the structural information of the data is exploited to guide the unmixing. Since similar pixel spectra often imply similar substance constructions, clustering can explicitly characterize this similarity. Through maintaining the structural information during the unmixing, the resulting fractional abundances by the proposed algorithm can well coincide with the real distributions of constituent materials. Moreover, the additional clustering-based regularization term also lessens the interference of noise to some extent. The experimental results on synthetic and real hyperspectral data both illustrate the superiority of the proposed method compared with other state-of-the-art algorithms. ? 1980-2012 IEEE.Accession Number: 20141217495307